njected W Base W
W
CTsec
II
CTprim

IECEQUATION18059 V1 EN-US (Equation 3)
The phase angle for all three injected current on the test set shall have the same
value of zero degree. As a consequence the, PSTPDIF function will work in either
of the following two ways:
• Trip, if parameter ZSCurrSubtrW2 = Off and all three differential currents and the bias current
shall be 100%. These values are available as outputs and service values from the PSTPDIF
function.
• Not trip, if parameter ZSCurrSubtrW2 = On and all three differential currents and the bias
current shall be 0%. These values are available as outputs and service values from the
PSTPDIF function.
11.3.5.6 Verifying the three-phase pickup from winding two side
GUID-11BB9D92-941D-4803-A319-578A049A7743 v1
1. Connect the test set for three-phase currents injection to the current terminals of the IED, which are
connected to the CTs on the winding two side of the power transformer.
2. Inject symmetrical three-phase currents (for example, positive sequence current only). Increase the
current magnitude symmetrically in all three phases until the protection function operates and note
the operating current. The operating secondary current should have the following value:
ickup Base W
W
CTsec
IIdMinI
CTprim

IECEQUATION18060 V1 EN-US (Equation 4)
The pickup current is independent of the actual phase angle shift across the
protected PST.
3. Check that the trip and alarm contacts operate according to the configuration logic.
4. Decrease the current slowly from the operate value and note the reset value.
5. Switch off the currents and connect an external timer to measure the operate time of the function.
Set the current in all three phases to twice the above measured pickup value.
6. Switch on the currents and note the operate time of the PSTPDIF function.
7. Check that the trip information is stored in the IED internal Event List and Disturbance Recorder.
8. Check that the trip information is properly indicated on the LHMI LEDs.
11.3.5.7 Verifying the single-phase pickup from winding two side
GUID-1DB4BF90-236B-4F15-A5A4-8BB6327CBF2B v1
1. Connect the test set for three-phase currents injection to the current terminals of the IED, which are
connected to the CTs on the winding two side of the power transformer.
2. Increase the current magnitude in phase L1 only until the protection function operates and note the
operating current. The secondary current at the moment of pickup will be greater for a certain factor
from the measured three-phase pickup value depending on the set value for the parameter
ZSCurrSubtrW2 and the actual phase angle shift across the protected power transformer for which
the test is conducted, as explained below:
• When ZSCurrSubtrW2 = Off, this factor will have a value between 1.00 and 1.50 depending
on the actual phase angle shift as shown in
Figure 23:
Section 11 1MRK 504 165-UUS Rev. J
Testing functionality by secondary injection
104 Transformer protection RET670
Commissioning manual
© 2017 - 2021 Hitachi Power Grids. All rights reserved
To Next Page
Loading...
Need help?
General
